I just registered to comment on this. I found this thread and it helped me solve my cruise issue on my 05 Freestar. Like the others, my cruise would work once in a blue moon, usually I'd see a very quick flash of the green cruise light on the dash, and then it would shut off. The cruise would never take over.
I bought a part from the local dealer, they had to order it in, but it only took about 2 hours from the warehouse.
The part was $22.22 and was quite small. All I needed was a adjustable wrench and a small screwdriver to get the electrical connector pryed off.
The part is called a cruise control deactivation switch. Is sits right on the end of the bottom of the brake master cylinder under the hood. When you take the old one out the brake fluid starts to run out, but there's plenty of time to get the new one threaded in before the brake fluid gets below the minimum mark. It's kinda weird getting it to thread, but you don't need to do anything special, just turn it, until it finally catches and goes on.
Plug the new connecter into the old wiring, and BINGO, it works again.
You need a turkey baster or something of the likes to replenish the lost brake fluid.
Now, i Just wish that I had found this thread and figured this out BEFORE my trip across the country. (but that's what gave me the motivation to figure it out, I guess)
Easy fix, anybody can do it! | 
